3.A.1.15.13The ZnuA18/ZnuA08/ZnuB/ZnuC zinc (Zn2+) uptake system (Hudek et al. 2013). ZnuB (M) and ZnuC (C) can function with either of two zinc ion receptors, ZnuA18 (R) which is encoded in the znuACB operon, and ZnuA08 (R) which is encoded elsewhere on the chromosome. ZnuA18 is more efficient that ZnuA08 in promoting uptake (Hudek et al. 2013).